1. Field of the Invention
The present invention relates to an optical fiber array having one or more optical fibers or an optical device having one or more optical waveguides, and more particularly to an optical device suitable for monitoring signal light while it is being propagated through such optical transmitting means.
2. Description of the Related Art
For the present optical communication technology, it is important to monitor communication quality. Particularly, the monitoring of optical output plays an important role in the field of the wavelength multiplex communication technology.
In recent years, there have been growing demands for smaller sizes, higher performance, and lower costs in the optical output monitoring technology.
Heretofore, there has been proposed a technology disclosed in Japanese Laid-Open Patent Publication No. 2001-264594, for example. According to the proposed technology, an optical fiber is placed in a V-shaped groove in a glass substrate, and then a parallel groove is formed obliquely (to the optical axis) in and across the optical fiber. A light reflecting base (optical member) is inserted into the parallel groove, with the gap filled with an ultraviolet-curable resin (adhesive).
Of signal light propagated through the optical fiber, a light component (reflected light) reflected by the light reflecting base is extracted out of the cladding. The reflected light is detected by a photodetector to monitor the signal light.
For connecting an optical path such as an optical fiber or the like with a low loss, there has been employed an optical fiber splicing resin or a refractive index matching material.
Generally, the optical fiber splicing resin comprises a resin having a Young's modulus ranging from several MPa to several GPa for the purpose of fixing an optical fiber in a certain position. If the optical fiber splicing resin is used as the resin that fills the parallel groove, then since the parallel groove which has a width of about several tens μm is filled with the hard resin having such a large Young's modulus, excessive stresses are developed, tending to give rise to a reliability problem, for example.
If the refractive index matching material is used as the resin that fills the parallel groove, then since the refractive index matching material is generally in a low-viscosity liquid phase, it is difficult to keep the refractive index matching material filled in the parallel groove, tending to result in a low yield.